The invention relates to a process for refining heavily contaminated scrap aluminum using a melt made up of salts of alkali or alkaline earth chlorides and fluorides.
Particles of glass, oxides and stones are in general very harmful when refining heavily contaminated scrap aluminum, especially when the concentration of aluminum is below 50 wt %. The removal of such foreign matter has caused considerable difficulty when employing the conventional technology for this purpose. Before electrolytic purification however, whether by three layer electrolysis, bipolar electrolysis or fractional crystallisation, the contaminating particles of solid material must be removed.
The salts employed by the secondary aluminum industry today in conventional processes are consumed to an excessive degree because of the high concentration of oxides.
The object of the present invention is therefore to develop a process for purifying heavily contaminated scrap aluminum, using a melt of molten salts of alkali and alkali earth chlorides and fluorides, and this such that the said process is economical and operates with a high degree of efficiency.